This application is based upon and claims priority to German Patent Application 1 99 51 885.8 filed Oct. 28, 1999, which application is herein expressly incorporated by reference.
The invention relates to a coupling that couples several hydraulic pipes and has a number of single couplings corresponding to the number of the to be connected pipes. The single coupling includes, in a known manner, two coupling members, a connector and a muff to receive the connector.
In mobile hydraulics, several hydraulic pipes have to be connected and disconnected from one another. Normally a basic vehicle has hydraulic pumps and control valves and various attachable equipment which include hydraulic drives that are supplied with hydraulic energy. If such attachable equipment is connected to the basic vehicle, for example a tractor, up to ten hydraulic pipes may be attached to the hydraulic system. To facilitate the coupling processes, several individual (single) hydraulic couplings are connected to a multi-coupling. Accordingly, several single hydraulic coupling members are installed in a common housing block. Connection means are connected to a second housing block which correspond to second coupling members. Often lever connections are used so that, with a single connection lever, several pipes can be connected to each other. One advantage of the couplings is that several hydraulic pipes, via single couplings, are coupled at the same time. Also, the coupling eliminates any confusion of the pipes of the two housing blocks being connected to each other in the wrong position. If a connection error takes place, dangerous malfunction may take place in the attaching equipment. This may lead to equipment damage.
A further problem exists in the couplings of hydraulic pipes. The problem is that the coupling is coupled against a back pressure in one or in two pipes. A very high pressure can build up due to different temperatures in the consumer pipe, the consumer pipe usually being the male coupling member. Also, a very high pressure may be present in the coupling muff, which is often connected by a pipe to the control valve and the pressure supply. During coupling of such hydraulic lines, which are highly pressurized, the pressure increases to such a high level that a coupling-in process is only possible by applying a higher force. During coupling, soft seals such as O-rings are attacked by the pressure medium which flows under high pressure. Leakages may occur. In couplings that have several single couplings that are coupled at the same time, the necessary coupling force is correspondingly multiplied. Then correspondingly stable tensioning levers, as they are for example disclosed in EP 0 522 493 B1 or DE 43 38 665 A1, are necessary to achieve such forces.
EP 0 686 801 A1 discloses a flat valve coupling, which is supposed to be suitable to protect the seals from destruction by a medium passing the seals. However, in this design, fluid has to be displaced during the coupling process and the coupling forces are correspondingly high.
To avoid the coupling problem under pressure, single couplings are used more often, in which the valves of the single coupling members are only opened after the coupling process. To open the valves, a lever mechanism is provided. The lever is actuated after coupling of the coupling members. Here, the real coupling process is easier, even if the pipes are under pressure. This is due to the fact that an opening of the valves does not take place during coupling, but only afterwards by a lever mechanism. The problem of coupling under pressure is practically solved, as for example disclosed in DE 43 18 840 C2. Here, a switching pin is provided which is axially displaced by a cam-like switching element. Thus, both valves of both coupling members are opened. A design of a flat connector can be selected for this type of coupling. Thus, during coupling, the coupling is oil leakage-free as the coupling valves are closed before coupling or decoupling.
It is an object of the present invention to provide couplings that are connected to a multi-coupling which secure simple coupling and decoupling and are oil leakage-free during coupling and decoupling.
This object is solved according to the invention by a coupling for coupling several hydraulic pipes that has a number of single couplings corresponding to a number of the to be connected pipes. Each coupling includes a first coupling member with a first valve having a first front face, to which the first valve is to be opened. Each coupling has a first cylindrical face, starting from the first front face. Each coupling has an actuating element that transfers the first valve into an open position. Each coupling has a sealing sleeve that is adjustable with a bore on the first cylindrical face in the direction of a longitudinal axis. The sleeve is displaceable by the actuating element from a retracted position into a projected position partly projected beyond the first front face. Each coupling includes a second coupling member that includes a second valve with a second front face to which the second valve is to be opened. Each coupling has a second cylindrical face at least partly covering the sealing sleeve in the projected position.
A first block housing is included which receives the first coupling members. A second block housing is included which receives the second coupling members in a position corresponding to the first coupling members. The second block housing is attachable to the first block housing.
The actuating element, over a first adjusting path, only adjusts the sealing sleeve to the projected position. In a subsequent second adjusting path, the actuating element displaces the first valve into the open position. Accordingly, a sealed connection is achieved before opening the first valve and second valve, which opening takes place at the same time.
The sealing sleeve in its bore has two sealing rings. The rings are arranged at a distance to each other to seal towards the first cylindrical face and the second face.
In a further embodiment, an adjustment spring is provided. The spring returns the sealing sleeve into the retracted position. The displacement into the projected position takes place against the force of the adjustment spring. If a closing of the first valve takes place via the actuating element, the sealing sleeve returns under the effect of the adjustment spring into the retracted position.
If the actuating element is designed as a pivot lever, pivoting moves the first valve from the closed position into the open position or vice versa. A cam disc impinges a collar of the sealing sleeve to displace it into the projected forward position. The cam disc is designed so that a first displacement of the sealing sleeve takes place to its final projected position via a predetermined rotational path or pivoting path of the actuating element. Afterwards, no further displacement takes place. To retain the projected position of the sealing sleeve, the cam disc has an adjustment circumferential contour. The contour extends around the axis of rotation of the actuating element formed as an actuating lever along an arc of a circle. The radius of the arc is kept constant. In using the adjustment mechanism described in U.S. Pat. No. 5,316,033, it is advantageous that free travel is given via a predetermined pivoting path between the switching element, which impinges the valve to be opened, and the actuating element, adjusted by this and which comprises a switching shaft. The switching shaft can be used to adjust the sealing sleeve. During further pivoting of the actuating element or the actuating lever, an adjustment of the switching element takes place. Thus, the first valve is displaced into the open or into the closed position. When moving from the open position into the closed position a passing of the free travel also takes place, and then the closing of the first and the second valve occurs. After this the adjustment spring becomes effective, so that the sealing sleeve is returned into its original position.
Two arrangements in the two block housings can be selected. In the first arrangement, the two coupling members of the single couplings are directly opposed to each other and support each other. However, in the connection of several coupling units or single couplings at the same time, corresponding pressures are active. Accordingly, it is possible that one or several coupling members are under high pressures while the neighboring couplings are not. This results in a load unbalance, which additionally loads the connection elements for the two block housings. To minimize these loadings, a further embodiment of the invention provides a sealing sleeve in the projected position which engages, extends into, an annular chamber formed between the second cylindrical face of the second coupling member and a bore of the second block housing.
In the second arrangement, the first block housing is formed by separate parts and has a cover plate. The second block housing abuts the cover plate of the first block housing in the connected condition. Therefore, a direct support of the two block housings takes place. The coupling members are not supported on each other. Accordingly, deformation is prevented. The existing sealing sleeves and the selected actuation lead to no leakage when the two coupling members are not abutting one another.
One large problem of all hydraulic couplings is that they can get dirty, especially when used in agricultural equipment. In quick connection couplings, where one coupling member is formed as a connector, and inserted into a second coupling member formed as a muff, and held by retaining balls which engage a sliding sleeve, it is difficult to keep the relatively narrow inlet opening of the muff clean. If after decoupling of a connector the inlet is not closed-up by special sealing caps or if these are defective, it is difficult to clean the inlet. If they cannot be cleaned, penetrated dirt will also be locked in during the coupling process and enter the hydraulic pressure medium. The danger of contamination is especially high in mobile hydraulics since the equipment is often used on building sites and it is extensively spread in agriculture. In such multi-couplings, comprising several single couplings, the danger also exists, that contaminations are locked in during coupling. Cleaning is easier since a whole row of individual coupling members need not be checked and if necessary to be cleaned during each coupling. The majority of multi-couplings are provided with flat valve connectors. Thus, the individual locking elements, which make the access difficult, can be deleted. To prevent damage or contamination of the second cylindrical face of the second coupling member, a protective sleeve is provided and adjustably inserted in the annular chamber. The protective sleeve has an end face, which, in the projected position, is flush with the second front face. The protective sleeve is impinged on by a spring to take up this projected position. Further, the protective sleeve is displaceable by the sealing sleeve into a retracted position.
From the following detailed description, taken in conjunction with the drawings and subjoined claims, other objects and advantages of the present invention will become apparent to those skilled in the art.
Preferred embodiments of the present invention are shown schematically (diagrammatically) in the drawings wherein:
FIG. 1 is a schematic view of a three coupling member arrangement arranged in a block housing and to be coupled to each other.
FIG. 2 is a cross-sectional view through a coupling unit to be connected likewise to each other, after fixing the two block housings to each other, however before the actual opening of the two valves of the coupling members.
FIG. 3 is a view similar to FIG. 2, where the two coupling members completely couple and the two valves of the coupling members open.
FIG. 4 is a schematical view of the actuating element with the cam disc for setting of the sealing sleeve.
FIG. 5 is a view according to FIG. 4 where the actuating element is in a second position.
FIG. 6 is a cross-sectional view of an embodiment where the block housings are supported relative to each other.
FIG. 7 is a cross-sectional view like FIG. 6, however the annular chamber is extended and receives a protective sleeve.
FIG. 8 is a cross-sectional view like FIG. 7 with the sealing sleeve displaced into its projected position and the protective sleeve extending into the annular chamber.